Crushed Clay Brick Research Articles

Properties and Performance of Concrete Made with Recycled Low-Quality Crushed Brick

During the past decades, in most industrialized countries, a large number of old buildings have been demolished and millions of tons of construction debris have been produced. Demolition wastes around cities have become a serious environmental issue and a threat to underground water quality and result in unpleasant views. Today, less than 5% of clay bricks taken from demolition sites are being separated and recycled, whereas the proportion of concrete waste being recycled is above 90%. This low rate of brick recycling is due to a lack of understanding about the performance of crushed brick material as aggregate in concrete or road base. In the case of concrete, the high water absorption of crushed brick and its relatively low compression strength in comparison with natural aggregate makes it difficult to meet traditional concrete specifications. The present research is an effort to investigate the properties of crushed clay bricks taken from demolition sites and experimentally evaluate the strength and durability characteristics of the concrete prepared using the crushed clay bricks. The experimental data reveal that, in spite of high porosity and absorption of recycled crushed brick, using this material as aggregate results in a semilightweight, durable, and low-permeability concrete.

Recycling of Crushed Clay Brick as Aggregate in Concrete

Clay brick generated from construction project sites is usually delivered to landfills for disposal and thus they can damage environment. The use of crushed clay brick can solve the environmental problem. This paper presents the possible use of crushed clay brick as a construction material. This new material gathered from some construction project sites in Iran is used as 100% aggregate in the production of concrete. The results indicated that the crushed clay brick reduced the unit weight and compressive strength of concrete, and increase the water absorption value. This new concrete can be used in non-structural products.

PROPERTIES OF HARDENED CONCRETE USING CRUSHED CLAY BRICK AS AGGREGATES

This paper provides the result of an investigation to use of crushed clay brick asaggregates in producing concrete. Eight different crushed clay brick aggregate concretes wereused in this investigation. Compressive strength, splitting tensile strength and pulse velocity ofcrushed clay brick aggregates concrete were determined and compare to natural aggregateconcrete. The compressive strength of crushed clay brick aggregates concretes were alwayslower than the compressive strength of natural aggregates concrete regardless the age ofconcrete, but the crushed clay brick aggregates concrete showed better performance as the age ofconcrete increases and average reduction in compressive strength were 33.5% at the age of 7days but it becomes only 20% at the age of 56 days compared to natural aggregates concrete. Thesplitting tensile strength of crushed clay brick aggregates concrete were always lower thannatural aggregate concrete, the reduction in splitting tensile strength of crushed clay brickaggregates concrete is ranging between 11 and 26% with an average reduction of about 18.5%compared to natural aggregates concrete. The pulse velocity of crushed clay brick aggregatesconcrete were also lower than natural aggregates concrete, the reduction in pulse velocity ofcrashed clay brick aggregates concrete is ranging between 6 and 22% with an average reductionof about 14% compared to natural aggregates concrete.

Use of wastes derived from earthquakes for the production of concrete masonry partition wall blocks

Utilization of construction and demolition (C&D) wastes as recycled aggregates in the production of concrete and concrete products have attracted much attention in recent years. However, the presence of large quantities of crushed clay brick in some the C&D waste streams (e.g. waste derived collapsed masonry buildings after an earthquake) renders the recycled aggregates unsuitable for high grade use. One possibility is to make use of the low grade recycled aggregates for concrete block production. In this paper, we report the results of a comprehensive study to assess the feasibility of using crushed clay brick as coarse and fine aggregates in concrete masonry block production. The effects of the content of crushed coarse and fine clay brick aggregates (CBA) on the mechanical properties of non-structural concrete block were quantified. From the experimental test results, it was observed that incorporating the crushed clay brick aggregates had a significant influence on the properties of blocks. The hardened density and drying shrinkage of the block specimens decreased with an increase in CBA content. The use of CBA increased the water absorption of block specimens. The results suggested that the amount of crushed clay brick to be used in concrete masonry blocks should be controlled at less than 25% (coarse aggregate) and within 50–75% for fine aggregates.

Effect of Crushed Clay Brick as Coarse Aggregate on Creep Behavior of Concrete

Difference between creep behaviors of concrete made from stone chips and crushed clay bricks, i.e. brick chips as coarse aggregate are examined by means of creep testing on their representative samples. Two different grades of concrete 17.2 and 27.5 N/mm2 are prepared from brick chips and stone chips using appropriate mix design and are tested for creep for up to 50 days. Stone chips and brick chips aggregates used are selected in a way so that their gradation and fineness modulus remains as close as possible. Results from creep testing shows that concrete made from brick chips as coarse aggregate having same strength as that of concrete made from stone chips shows higher creep strain. As concrete strength increases, the difference in creep strain becomes more pronounced. Also, at initial loading condition, concrete made from brick chips shows higher rate of creep strain than that of concrete made from stone chips.

Concrete with recycled concrete aggregate and crushed clay bricks

In the last two decades, a variety of recycling methods for construction and demolition wastes (CDW) have been developed. For instance, as one of the major components in CDW, concrete rubble has been used to replace natural aggregate after being treated. This is known as recycled concrete aggregate (RCA). The property and use of RCA for structural or non-structural concrete have been extensively studied and numerous findings have been adopted in engineering practice to produce sustainable concrete. Concrete rubble, however, is inevitably mixed with other wastes such as crushed clay bricks (CCB). The level of inclusion varies depending on the original construction materials of demolished buildings. The differing properties of CCB from RCA will affect the mix design as well as the physical and mechanical properties of the resulting new concrete when the inclusion level exceeds a certain limit. Separating CCB from RCA presents an operational difficulty in practice and also has huge cost implications. Therefore, it is important to study the effect of CCB with various inclusion levels on the properties of fresh and hardened concrete. This paper reports on a study conducted to investigate the physical and mechanical properties of recycled concrete with high inclusion levels of RCA and CCB and to explore the potential or the limitation of this type of mixed recycled aggregate in primary concrete structures.

Effects of crushed clay brick aggregate on mortar durability

This paper reports an experimental study that aimed to investigate the effects of recycled clay brick, used as a part of fine aggregate, on mortar durability. The brick, in crushed form, was from a local brick manufacturer that salvages its off-standard products. It was used to replace 10% and 20% (by weight) of the river sand in mortar. Effects of the brick replacement on the mortar flow, compressive strength, shrinkage, freeze–thaw resistance, and alkali–silica reaction potential were investigated. The results showed that as the brick replacement level increased, the mortar flowability reduced. The 10% and 20% brick replacements had no negative effect on the mortar compressive strength and very limited effect on the mortar shrinkage. The freeze–thaw resistance of the mortar was improved by the brick replacement. However, the use of crushed brick as aggregate appeared not to reduce potential alkali–silica reaction. The microscopy study revealed the alkali–silica reaction product and associated cracking in the mortar. Additional study indicated that the brick aggregate used in the study had pessimum proportion, 30%, for the alkali–silica reaction expansion.

Discussion of “Using Crushed Clay Brick as Coarse Aggregate in Concrete” by Fouad M. Khalaf

Discussion of “Using Crushed Clay Brick as Coarse Aggregate in Concrete” by Fouad M. Khalaf

Closure to ‘Using Crushed Clay Brick as Course Aggregate in Concrete’ by Fouad M. Khalaf

Closure to ‘Using Crushed Clay Brick as Course Aggregate in Concrete’ by Fouad M. Khalaf

Using Crushed Clay Brick as Coarse Aggregate in Concrete

This paper provides the results of an experimental investigation into the use of crushed new clay brick as coarse aggregate in producing concrete. The present investigation is the first phase of a two-phase program to study the effects of using recycled masonry aggregate (predominately made of clay brick) with its impurities on the properties of fresh and hardened concrete. Four different types of new clay bricks with different compressive strengths were used in the investigation. Several physical and mechanical properties of fresh and hardened concrete produced from crushed clay brick aggregates were determined and compared to concrete produced using granite as a proven aggregate.

Paving blocks made with recycled concrete aggregate and crushed clay brick

Clay brick generated from construction sites is usually delivered to landfills for disposal. With the limited landfill space in Hong Kong, there is an immediate need to explore the possible use of crushed clay brick as a new civil engineering material. In Hong Kong, government specifications promote the use of paving blocks made with 70–100% recycled concrete aggregate in order to facilitate the recycling of construction and demolition (C&D) waste. This paper presents a recent study at the Hong Kong Polytechnic University on the investigation of blending recycled concrete aggregate and crushed clay brick as aggregates in the production of paving blocks. The results indicated that the incorporation of crushed clay brick reduced the density, compressive strength and tensile strength of the paving blocks. Due to the high water absorption of crushed clay brick particles, the water absorption of the resulting paving blocks were higher than that of the paving blocks that did not incorporate crushed clay brick. Although it was found that crushed clay brick impaired the quality of the resulting paving blocks to a certain extent, the paving blocks using 50% crushed clay brick met the minimum requirements specified by AS/NZS 4455 and ETWB of Hong Kong (Grade B) for pedestrian areas. Furthermore, it was feasible to produce paving blocks prepared with 25% crushed clay brick that satisfied the compressive strength requirement for paving blocks (Grade B) prescribed by ETWB of Hong Kong for trafficked area.

Feasible use of recycled concrete aggregates and crushed clay brick as unbound road sub-base

A study was recently conducted at the Hong Kong Polytechnic University to investigate the possibility of using recycled concrete aggregates and crushed clay brick as aggregates in unbound subbase materials. The results showed that the use of 100% recycled concrete aggregates increased the optimum moisture content and decreased the maximum dry density of the subbase materials compared to those of natural subbase materials. Moreover, the replacement of recycled concrete aggregates by crushed clay brick further increased the optimum moisture content and decreased the maximum dry density. This was mainly attributed to the lower particle density and higher water absorption of crushed clay brick compared to those of recycled concrete aggregates. The CBR values (unsoaked and soaked) of the subbase materials prepared with 100% recycled concrete aggregates were lower than those of natural subbase materials. The CBR values further decreased as the replacement level of recycled concrete aggregates by crushed clay brick increased. Nevertheless, the soaked CBR values for all recycled subbases were greater than 30%, which is a minimum strength requirement in Hong Kong. Furthermore, the recorded percentage swells for all subbases were less than 0.13% which can be considered negligible.

Performance of Brick Aggregate Concrete at High Temperatures

This paper presents the results of an experimental investigation into the effects of high temperatures on the properties of concrete made with crushed clay bricks as the coarse aggregate. Two types of brick of different strength were crushed to coarse aggregate that was used to produce concretes of different strength. Natural granite aggregate was also used to produce concretes in order to compare results. The paper presents the results for brick unit uniaxial compressive strength, aggregate impact value, aggregate relative density, brick and aggregate water absorption, aggregate porosity, concrete density, and concrete strength before and after exposure to high temperatures. The results showed that concrete could be produced using crushed clay bricks as the coarse aggregate and at high temperatures clay brick concrete preformed similar or even better than granite concrete.

Crushed Bricks as Coarse Aggregate for Concrete

The suitability of crushed clay bricks as coarse aggregate for concrete has been assessed by comparing its basic properties with that of conventional concrete. Four basic mixes were chosen for crushed granite to achieve concrete with grades from 30 MPa to 60 MPa. The equivalent brick-aggregate concrete for each mix was obtained by replacing granite with an equal volume of crushed bricks, everything else remained the same. Test results indicate that brick-aggregate concrete can attain the same compressive strength, gives a higher tensile strength, a lower drying shrinkage, and almost identical specific creep when compared with conventional concrete. However, it exhibits a substantially smaller elastic modulus. Also, the peak stress is reached at a much higher strain. An equation is presented to generate the complete stress-strain curve of brick and granite-aggregate concretes with a good degree of accuracy.

Mortar Study of Mechanical Properties for the Repointing of the Canadian Parliament Buildings

This paper contributes to the ongoing conservation work for stone masonry structures on the Parliamentary Precinct in Ottawa, Canada. A major part of the work focuses on deep repointing of Nepean sandstone masonry. To help define durable repointing mortars, two related test programs were commissioned by Parks Canada/Environment Canada/Public Works and Government Services Canada (PWGSC) in 1994-95; these programs essentially dealt with mechanical properties and frost durability. While work on the mechanical properties is the subject of this paper, a companion paper deals with the frost durability testing [1]. Together they represent the first comprehensive test program on repointing mortars where both mechanical properties and frost durability are examined together. Previous work carried out in the early 1990s concentrated on selected mechanical properties, including the bond between various mortars and masonry units [2]. Throughout the current test programs two basic mortar types were used: masonry cement (MC) and portland cement-lime (PC-L) mortars. Mortarmaterial variables included the type of lime (hydrated types N or S, lime putty, and hydraulic lime) and partial sand replacement by means of crushed clay brick and clay brick dust. At the outset 26 trial mixes were prepared to determine their plastic properties and help select workable mixes for later specimen construction. The trial-mix work was followed by two phases of mortar mixes, including specimen construction for mechanical property and frost-durability testing. While phase 1 involved 17 mixes over a wide range of mortar material variables, phase 2 concentrated on 16 mixes within a narrower range of material variables. Recommended repointing mixes for the conservation work on the Parliamentary Precinct structures came from the refined phase 2 mixes. Because conservation work typically requires relatively low-strength, softer mortars, mortar proportions corresponded to type N or weaker mixes throughout the test programs. The determination of mechanical properties included the mortar's compressive and split-tensile strengths, as well as its modulus of elasticity, and the masonry's flexural bond strength. The test results were judged against a set of performance criteria that represent a first attempt to delineate such criteria for repointing mortars. This paper provides an overview of the mechanical test program for Nepean sandstone mortars, summarizes key results, and gives recommendations for suitable mortar mixes and future work. Further details are presented elsewhere [3].